Due to a rapid further development of sensors and systems, an increasingly accurate detection of the vehicle surroundings is made possible. Different driver assistance systems may thus support the human driver in his or her driving task, and/or assume parts of the tasks completely. Various active and passive sensors work with the aid of different electromagnetic spectral ranges. Depending on the spectral range, more or less strong damping and scattering effects may occur due to atmospheric phenomena (rain, fog, . . . ). For cameras (spectral range approximately in the range of the visible light), mainly fog may in this way result in visibility limitations.
European Patent No. 1303768 describes a method for visibility range determination. To determine the visibility range in particular of a driver in a vehicle, a contrast is measured from at least two measuring positions of a measuring device, the positions being spaced at different distances from the object, and the relation of the measured contrast values is converted into a visibility range based on the difference of the distances of the measuring positions from the object.